Thursday's MRI revealed a muscle strain in Santiago's pitching shoulder, Phil Miller of the Minneapolis Star Tribune reports.

EDGE Analysis

The southpaw is already on the disabled list due to a left shoulder injury, and Thursday's MRI confirmed the team's expectation that he is dealing with a strain. Miller adds that the muscle strain is located on the back of Santiago's shoulder. There's still no firm timetable for Santiago's return at this point, which makes the recently claimed Chris Heston a possible rotation stop-gap for the time being.